[PATCH 11/11] nvmet: add an FDP write translation tracepoint

[Guixin Liu]

Add a tracepoint to the write path that reports the placement
identifier carried by a write command with the Data Placement
Directive and the backing write stream it is translated to.

Signed-off-by: Guixin Liu <kanie at linux.alibaba.com>
---
 drivers/nvme/target/io-cmd-bdev.c |  8 ++++++++
 drivers/nvme/target/trace.h       | 23 +++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index 832b406442440..a8f3ad736335f 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -9,6 +9,7 @@
 #include <linux/memremap.h>
 #include <linux/module.h>
 #include "nvmet.h"
+#include "trace.h"
 
 void nvmet_bdev_set_limits(struct block_device *bdev, struct nvme_id_ns *id)
 {
@@ -305,6 +306,13 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
 	    nvmet_fdp_enabled(req->ns)) {
 		write_stream = nvmet_fdp_write_stream(req);
 		bio->bi_write_stream = write_stream;
+
+		if (write_stream) {
+			u16 pid = le32_to_cpu(req->cmd->rw.dsmgmt) >> 16;
+
+			trace_nvmet_fdp_write_translate(req, pid,
+							write_stream);
+		}
 	}
 
 	blk_start_plug(&plug);
diff --git a/drivers/nvme/target/trace.h b/drivers/nvme/target/trace.h
index 7f7ebf9558e50..0ab7252960790 100644
--- a/drivers/nvme/target/trace.h
+++ b/drivers/nvme/target/trace.h
@@ -131,6 +131,29 @@ TRACE_EVENT(nvmet_req_complete,
 
 );
 
+TRACE_EVENT(nvmet_fdp_write_translate,
+	TP_PROTO(struct nvmet_req *req, u16 pid, u8 stream),
+	TP_ARGS(req, pid, stream),
+	TP_STRUCT__entry(
+		__field(u16, ctrl_id)
+		__array(char, disk, DISK_NAME_LEN)
+		__field(u32, nsid)
+		__field(u16, pid)
+		__field(u8, stream)
+	),
+	TP_fast_assign(
+		__entry->ctrl_id = nvmet_req_to_ctrl_id(req);
+		__assign_req_name(__entry->disk, req);
+		__entry->nsid = req->ns->nsid;
+		__entry->pid = pid;
+		__entry->stream = stream;
+	),
+	TP_printk("nvmet%s: %snsid=%u, pid=%u, write_stream=%u",
+		__print_ctrl_id(__entry->ctrl_id),
+		__print_disk_name(__entry->disk),
+		__entry->nsid, __entry->pid, __entry->stream)
+);
+
 #define aer_name(aer) { aer, #aer }
 
 TRACE_EVENT(nvmet_async_event,
-- 
2.43.7